The present invention relates to a sensor which can be attached to a surface of a base member above an object which is definedly movable relative to the base member. The sensor has, at its front end, a measuring surface which is to be arranged at a defined small distance from the object for measuring its movement. The sensor comprises a lateral retaining arm which contains a through guide bore extending substantially vertically to the measuring surface and accommodates, with a sliding fit, a substantially circular-cylindrically designed carrier member. This carrier member contains a narrow central bore for receiving a fastening bolt which serves to fix the carrier member in position on the surface of the base member which extends substantially in parallel to the measuring surface. The sensor is adjustable in parallel to the axis of the carrier member and around this axis and can be secured in a set position in relation to the base member.
In such a known sensor, the lateral arm of the sensor can be clamped with the carrier member by means of an additional lateral clamping bolt, while the carrier member, in turn, is clampedly fixed on the base member by the head of the fastening bolt. Before the lateral bolt is tightened, the sensor can be adjusted in parallel to the axis of the carrier member and around this axis for giving the sensor an optimal alignment and an optimal distance with respect to the movable object. In a preferred embodiment, the movable object may consist of a toothed disc which acts magnetically on a coil arrangement ending in the area of the measuring surface. One or two pole pieces provided in the area of the measuring surface sense the passage of the tooth.
For securing this sensor, two bolts are provided and these must be tightened in two subsequent working steps.